This invention relates to a heat engine.
The heat engine is an alternate engine to the internal combustion engine. Various designs for heat engines have been developed in the past. Despite its potential for greater thermodynamic efficiency compared to internal combustion engines, heat engines have been used in only limited applications in the past due to several factors including the complexity of the designs, the weight of the engine per unit of horse power output as well as the difficulty in starting a heat engine.
In accordance with the instant invention, an improved design for a heat engine is disclosed. In one embodiment, the heat engine is made from lightweight sheet metal. By using a plurality of cylindrical containers, one nested inside the other, for the displacer, the combustion and cooling chambers as well as to create an air flow path between the heating and cooling chambers, a rugged durable lightweight construction is achieved.
In another embodiment, the heat engine utilizes a power piston which is biased to a first position. By biasing the piston, several advantages are obtained. First, the heat engine may be self starting provided the power piston is biased so as to be initially positioned in the cooling chamber. A further advantage is that by using an electrical means (eg. a solenoid, an electromagnet or the like) to move the displacer, preferably in response to the position of the power piston, a complicated mechanical linkage between the power piston and the displacer is not required thus simplifying the design. Further, by using an electrical linkage, the phase angle between the displacer and the power piston may be adjusted.
The heat engine of the instant invention may be combined with a fuel source (eg. butane), a linear generator and an electrically operated light emitting means to create a flashlight or other portable light source. It will be appreciated that due to the simplicity of the design of the instant invention, the heat engine as well as the linear generator are each adapted to be scaled up or down so as to produce greater or lessor amounts of power. Accordingly, in another embodiment, the heat engine together with a linear generator and a fuel source may be used as a generator. It will further be appreciated that by connecting a linear generator to a source of electricity (eg. standard electrical outlet) the electricity from a power grid may be used to run the linear generator as a motor whereby the power piston effectively drives the displacer. In such a case, the heat engine may be used as a refrigerator or a cryogenic cooler. In such an embodiment, the heating and cooling chambers of the heat engine are effectively reversed and no combustion chamber is required.
In accordance with one aspect of the instant invention, there is provided a heat engine comprising a container defining a sealed region within which a working fluid is circulated when the heat engine is in use, the sealed region having a heating chamber and a cooling chamber, the heating and cooling chambers being in fluid flow communication via a working fluid passageway; a combustion chamber thermally connected to the heating chamber; a displacer movably mounted in the sealed region; a piston movably mounted in the sealed region; at least one cooling fin having first and second opposed sides and positioned exterior of the cooling chamber; and, a heat exchanger having a combustion air passageway for providing air for combustion to the combustion chamber, at least some of the cooling fins are positioned in the heat exchanger whereby heat withdrawn from the cooling chamber is a used to preheat the air for combustion.
In one embodiment, the at least one fin is configured and arranged to permit fluid to flow from the first opposed side to the second opposed side and to direct fluid from the second opposed side to the first opposed side.
In another embodiment, the at least one fin has main directing members and fluid flow passages through which the fluid may pass through the fin, the main directing members are configured and arranged to cause a portion of the fluid which has passed through the fin from the first opposed side to the second opposed side to then pass from the second opposed side to the first opposed side.
In another embodiment, the at least one fin is configured and arranged to cause at least a portion of the fluid to swirl around the combustion air passageway.
In another embodiment, the at least one fin has a deformable collar for lockingly engaging the wall to which the fin is attached.
In another embodiment, the at least one fin is mechanically mounted to at least one wall of the heat exchanger by a pressure which is exerted between the fin and the at least one wall which is sufficient to ensure that the rate of heat transfer between the at least one wall and the fin is maintained over the normal operating temperature of the at least one wall.
In another embodiment, the at least one fin comprises a plurality of longitudinally spaced apart fins.
In another embodiment, the at least one fin comprises a helical fin.
In another embodiment, the at least one fin has at least one main directing member which is configured and arranged to cause a portion of the fluid to pass at least twice through the main directing member as the fluid flows through the fin.
In another embodiment, the at least one fin has at least one main directing member which has a first side, a second side and is configured and arranged to cause a portion of the fluid to flow unidirectionally from the first side of a main directing member to the second side of the main directing member as the fluid flows through the fin.
In another embodiment, the at least one fin has a hub adjacent a wall of the combustion air passageway and an annular body portion extending away from the hub, and openings and main directing members are provided in the annular body portion.
In another embodiment, the at least one fin has a hub adjacent a wall of the combustion air passageway and a plurality of blades extending away from the hub, the blades defining passages through which air for combustion flows.
In another embodiment, the heat engine further comprises a motor driven fan mounted in fluid flow communication with the combustion air passageway for assisting in producing air flow through the combustion air passageway. Preferably, the motor and the fan encircle the heat engine.
In accordance with another aspect of the instant invention, there is also provided a heat engine comprising container means having first and second portions; fluid conduit means for connecting the first and second portions in fluid flow communication, the first portion is at a higher temperature than the second portion when the heat engine is in use; combustion means for receiving air for combustion and providing heat to the first portion; and, heat exchanger means for transferring heat from the second portion of the container means to the air for combustion, the heat exchanger means comprising fin means positioned in the heat exchanger means.
In one embodiment, the heat engine further comprises outer container means positioned exterior to the container means wherein each of the container means and the outer container means are thin walled, and positioning means, for dimensionally stabilizing the container means and outer container means, the heat exchanger means is positioned on the outer container means.
In another embodiment, the positioning means extends between the inner and outer container.
In another embodiment, the fin means is constructed to generate a generally longitudinal flow of fluid through the heat exchanger means.
In another embodiment, the fin means is constructed to generate a rotational flow of fluid through the heat exchanger means.
In another embodiment, the fin means comprises a plurality of rows of fins having first and second opposed sides, at least some of the fins having fluid directing means for directing the fluid from the first opposed side to the second opposed side and from the second opposed side to the first opposed side.
In another embodiment, the fin means comprises a plurality of rows of fins having first and second opposed sides, at least some of the fins having fluid directing means for directing fluid to flow rotationally through the heat exchanger means.
In another embodiment, the fin means has mounting means for producing a sufficient pressure between the fin means and the portion of the heat engine to which the fin means is mounted to ensure that the rate of heat transfer between the heat engine and the fin means is maintained over the normal operating temperature of the heat engine.
In another embodiment, the heat engine a further comprises fan means for providing forced convection in the heat exchanger means.
In another embodiment, the fan means is mounted in the heat exchanger means.
In another embodiment, the fin means have first and second opposed sides and first directing means for generating a main flow of fluid through the fin means as the fluid flows from the first opposed side to the second opposed side and second directing means for generating a secondary fluid flow which passes through at least some of the first directing means whereby the heat transfer between the fluid and the heat exchanger means is enhanced.
In another embodiment, the first directing means generates an axial flow of fluid through the heat exchanger means.
In another embodiment, the first directing mean generates a rotational flow of fluid through the heat exchanger means.
In another embodiment, at least some of the first directing means direct the fluid from the first opposed side to the second opposed side and from the second opposed side to the first opposed side.
In another embodiment, the fin means comprises a plurality of individual longitudinally spaced apart annular fins and/or a helical fin.
In another embodiment, the second directing means are configured and arranged to cause a portion of the fluid to pass at least twice through the first directing means with which the second directing means are associated as the fluid flows through the fin means.
In another embodiment, the main directing means has a first side, a second side, the second directing means is configured and arranged to cause the fluid to flow unidirectionally from one side of a main directing means with which the second directing means is associated to the other side as the fluid flows through the fin means.
In accordance with another aspect of the instant invention, there is also provided a heat engine comprising container means having first and second portions; fluid conduit means for connecting the first and second portions in fluid flow communication, the first portion is at a higher temperature than the second portion when the heat engine is in use; combustion means for receiving air for combustion and providing heat to the first portion; heat exchanger means for transferring heat from the second portion of the container means to the air for combustion; and, fan means for providing forced convection in the heat exchanger means.
In one embodiment, the fan means is mounted in the heat exchanger means.
In another embodiment, the fin means have first and second opposed sides and first directing means for generating a main flow of fluid through the fin means as the fluid flows from the first opposed side to the second opposed side and second directing means for generating a secondary fluid flow which passes through at least some of the first directing means whereby the heat transfer between the fluid and the heat exchanger means is enhanced.
In another embodiment, the first directing means generates an axial flow of fluid through the heat exchanger means.
In another embodiment, the first directing mean generates a rotational flow of fluid through the heat exchanger means.
In another embodiment, the second directing means are configured and arranged to cause a portion of the fluid to pass at least twice through the first directing means with which the second directing means are associated as the fluid flows through the fin means.
In another embodiment, the main directing means has a first side, a second side, the second directing means is configured and arranged to cause the fluid to flow unidirectionally from one side of a main directing means with which the second directing means is associated to the other side as the fluid flows through the fin means.